Vehicle control apparatus and method

ABSTRACT

Vehicle control apparatus and method are disclosed. A method for controlling a vehicle control apparatus includes: measuring a vehicle speed to measure a first vehicle speed and a second vehicle speed of a vehicle, calculating an error rate to calculate an error rate of a vehicle speed using the first vehicle speed and the second vehicle speed measured in the measuring of the vehicle speed, and correcting a vehicle speed to correct a speed of the vehicle by calculating a third vehicle speed of the vehicle based on the error rate calculated in the calculating of the error rate.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of Korean Patent Application No.2015-0128998, filed on Sep. 11, 2015 in the Korean Intellectual PropertyOffice, the disclosure of which is incorporated herein by reference.

BACKGROUND

1. Field

Embodiments of the present disclosure relate to a vehicle controlapparatus and a vehicle control method, and more particularly, to avehicle control apparatus and method for correcting a vehicle speed anddetermining a wheel abnormality using image information.

2. Description of the Related Art

As engine performance of vehicles increases, traveling speeds ofvehicles have increased. Accordingly, various electronic control systems(ECSs) are installed in vehicles for improving running stability andobtaining braking stability.

An ECS includes an anti-lock brake system (hereinafter, referred to asan ABS) which prevents slip of wheels during braking, a traction controlsystem (hereinafter, referred to as a TCS) which prevents slip of wheelsduring sudden unexpected acceleration, and an electronic stabilitycontrol (hereinafter, referred to as an ESC) in which the ABS and TCSare mixed to stably maintain a running posture of a vehicle, and thelike.

Such an ECS uses a wheel speed sensor which measures a speed of arunning vehicle for implementing appropriate control performance.

The wheel speed sensor measures the speed of the vehicle through aperiod of a pulse signal generated when a tone wheel installed at awheel and configured to rotate with the wheel rotates. The tone wheelhas a plurality of teeth or holes formed on a circular plate or acylindrical shape through which light passes, and pulses are generatedusing a difference between when the light passes through the teeth orholes and when it does not pass through the teeth or holes. In the caseof a vehicle, a rotational speed of a wheel, that is, a speed of thevehicle, is measured through the pulse signal.

However, such a wheel speed sensor has an inconvenience in that a speedof a vehicle is measured differently from an actual speed of the vehiclewhen a wheel of the vehicle is broken or replaced with another wheel, apressure of a tire installed at the wheel is high or low compared withits normal state, or the tire is broken.

PRIOR ART Patent Document

Korean Laid-Open Patent Publication No. 10-2005-0100990

SUMMARY

Therefore, it is an aspect of the present disclosure to provide avehicle control apparatus and method for correcting a vehicle speedusing image information.

In addition, it is another aspect of the present disclosure to provide avehicle control apparatus and method for determining a wheel abnormalityusing image information.

Additional aspects of the disclosure will be set forth in part in thedescription which follows and, in part, will be obvious from thedescription, or may be learned by practice of the disclosure.

In accordance with an aspect of the present invention, a vehicle controlmethod includes: measuring a vehicle speed to measure a first vehiclespeed and a second vehicle speed of a vehicle; calculating an error rateto calculate an error rate of a vehicle speed using the first vehiclespeed and the second vehicle speed measured in the measuring of thevehicle speed; and correcting a vehicle speed to correct a speed of thevehicle by calculating a third vehicle speed of the vehicle based on theerror rate calculated in the calculating of the error rate.

The method may further include: determining a wheel abnormality todetermine a wheel abnormality of the vehicle by comparing the thirdvehicle speed calculated in the correcting of the vehicle speed with thefirst vehicle speed.

The first vehicle speed may be a speed of the vehicle measured by awheel speed sensor, and the second vehicle speed may be a relative speedof an image captured by a camera with respect to the vehicle.

The error rate may be proportional to the sum of the first vehicle speedand the second vehicle speed and is inversely proportional to the firstvehicle speed.

The third vehicle speed may be proportional to the first vehicle speedand a difference between a reference value and the error rate.

The second vehicle speed may be a relative speed with respect to thevehicle based on an increased number of occupied pixels of a portion ofan image captured by a camera.

The second vehicle speed may be a relative speed with respect to thevehicle based on a degree of movement of occupied pixels of a portion ofan image captured by a camera.

The method may further include: correcting the first vehicle speed usingthe calculated third vehicle speed.

The first vehicle speed may include each wheel speed; the calculating ofthe error rate may include calculating the error rate of the vehiclespeed a plurality of times using each wheel speed included in the firstvehicle speed and the second vehicle speed; and the calculating of theerror rate may include calculating the third vehicle speed of thevehicle a plurality of times based on the plurality of error ratescalculated in the calculating of the error rate.

In accordance with another aspect of the present invention, a vehiclecontrol apparatus includes: a camera configured to capture a runningimage of a vehicle; a plurality of wheel speed sensors installed at eachwheel of the vehicle; and a controller configured to correct a pluralityof wheel speeds using the running image obtained by the camera and adetection result of the wheel speed sensors, wherein the controllerincludes: a relative speed calculator configured to calculate a relativespeed of the vehicle using the running image captured by the camera; anerror rate calculator configured to calculate an error rate of the wheelspeed using the relative speed and each of the wheel speeds; and avehicle speed corrector configured to correct each of the wheel speedsbased on the error rate.

The controller may further include a wheel abnormality determinationunit configured to respectively compare the wheel speeds detected by theplurality of wheel speed sensors and the corrected wheel speeds todetermine a wheel abnormality.

The relative speed calculator may calculate the relative speed of thevehicle based on an increased number of occupied pixels of a portion ofthe image captured by the camera; the error rate calculator maycalculate the error rate of the vehicle such that the error rate isproportional to a vehicle speed and the relative speed and inverselyproportional to the vehicle speed; and the vehicle speed corrector maycorrect each of the wheel speeds based on a corrected vehicle speedproportional to the vehicle speed and a difference between a referencevalue and the error rate.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects of the invention will become apparent andmore readily appreciated from the following description of theembodiments, taken in conjunction with the accompanying drawings ofwhich:

FIG. 1 is a block diagram illustrating a vehicle control apparatusaccording to an embodiment of the present invention.

FIG. 2 illustrates a camera image to represent the increasing number ofoccupied pixels of a portion of the camera image according to anembodiment of the present invention.

FIG. 3 illustrates a camera image to represent the degree of movement ofoccupied pixels of a portion of the camera image according to anembodiment of the present invention.

FIG. 4 is a flowchart illustrating a vehicle control method according toan embodiment of the present invention.

FIG. 5 is a block diagram illustrating a vehicle control apparatusaccording to an embodiment of the present invention.

FIG. 6 is a flowchart illustrating a vehicle control method according toan embodiment of the present invention.

DETAILED DESCRIPTION

Embodiments described in this specification and configurationsillustrated in drawings are only exemplary examples of the discloseddisclosure. The disclosure covers various modifications that cansubstitute for the embodiments herein and drawings at the time of filingof this application.

Hereinafter, a vehicle control apparatus for correcting a vehicle speedwill be described in detail with reference to one embodiment of thepresent disclosure.

As illustrated in FIG. 1, a vehicle control apparatus according to oneembodiment of the present disclosure includes a sensor 110, an imageacquisition unit 120, and a controller 130.

The sensor 110 detects a vehicle speed.

The sensor 110 may detect a wheel speed and transfer the detectionresult to the controller 130.

The sensor 110 may include a wheel speed sensor installed at a wheel todetect a wheel speed.

The wheel speed sensor may include a tone wheel installed at a wheel ofa vehicle and configured to rotate with the wheel and a sensing unitthat measures a period of a pulse signal generated when the tone wheelrotates.

The image acquisition unit 120 obtains a running image of a vehicle.

The image acquisition unit 120 may transfer the running image of thevehicle to the controller 130.

The image acquisition unit 120 may include a camera installed at thevehicle for obtaining the running image of the vehicle.

The camera may transfer the running image of the vehicle to thecontroller 130.

The camera may transfer the running image of the vehicle to thecontroller 130 with pixel information.

The pixel information may include the number of pixels included in oneframe and relative distances between the pixels.

The camera may transfer information about time intervals between theframes to the controller 130.

A camera for a black box installed in a general vehicle may be used asthe camera.

The controller 130 corrects a vehicle speed using a detection resultdetected by the sensor 110 and a running image obtained by the imageacquisition unit 120.

The controller 130 includes a relative speed calculator 131, an errorrate calculator 132, and a vehicle speed corrector 133.

The relative speed calculator 131 calculates a relative vehicle speedusing a running image captured by the image acquisition unit 120.

The relative speed calculator 131 may calculate the relative vehiclespeed using pixel information of the camera.

The relative speed calculator 131 may calculate the relative vehiclespeed based on an increased or decreased number of occupied pixels of aportion of the running image of the camera.

The relative speed calculator 131 may calculate a relative vehicle speedbased on an increasing number of occupied pixels when a running image ofa camera is a front image, and may calculate the relative vehicle speedbased on a decreasing number of occupied pixels when the running imageof the camera is a rear image.

When a vehicle moves backward, the relative vehicle speed may becalculated based on the decreasing number of occupied pixels when therunning image is the front image of the vehicle, and the relativevehicle speed may be calculated based on the increasing number ofoccupied pixels when the running image is the rear image of the vehicle.

The relative speed calculator 131 may determine whether a vehicle runsforward or backward based on a position of a running gear.

As illustrated in FIG. 2, the relative speed calculator 131 maycalculate the relative vehicle speed based on the increasing number ofoccupied pixels of a portion of a camera image.

The relative speed calculator 131 may calculate the relative vehiclespeed using Equation 1.

relative vehicle speed=(Δpixel/Δt)×K  [Equation 1]

Δpixel: a degree of change of occupied pixels

Δt: time change

K: a camera-property-based tuning variable

The camera-property-based tuning variable K is a fixed constantdetermined by specifications of a camera and a vehicle.

For example, when the number of occupied pixels of a sign board in a100^(th) frame is 4, the number of pixels of the sign board in a200^(th) frame is 16, a time interval of 100 frames is 0.1 sec, and thecamera-property-based tuning variable K is 0.5, the relative vehiclespeed is calculated as 60 m/s.

Here, since the relative vehicle speed is a relative vehicle speed withrespect to an object rather than a speed of the vehicle itself, therelative vehicle speed has a negative value.

In addition, as illustrated in FIG. 3, the relative speed calculator 131may measure the relative vehicle speed based on the degree of movementof occupied pixels of a portion of a camera image.

When the relative speed calculator 131 measures the relative vehiclespeed based on the degree of movement of occupied pixels, Δpixel inEquation 1 is defined as the degree of movement of occupied pixelsrather than the degree of change of occupied pixels.

When Δpixel in Equation 1 is defined as the degree of movement ofoccupied pixels rather than the degree of change of occupied pixels, thecamera-property-based tuning variable K may also be adjusted.

For example, when the degree of movement of occupied pixels of a trafficlane in the 100^(th) and 120^(th) frames is 2, a time interval of 20frames is 0.02 sec, and the camera-property-based tuning variable K is0.6, a relative vehicle speed is calculated as 60 m/s.

The relative speed calculator 131 may be included in the imageacquisition unit 120.

The error rate calculator 132 calculates an error rate of a vehiclespeed using a relative speed and a vehicle speed.

The error rate calculator 132 may calculate an error rate of the vehiclespeed using Equation 2.

error rate=(relative speed+vehicle speed)/vehicle speed  [Equation 2]

For example, when the relative vehicle speed is −30 m/s and the vehiclespeed is 20 m/s, the error rate is −0.5.

The vehicle speed corrector 133 corrects the vehicle speed based on theerror rate.

The vehicle speed corrector 133 may correct the vehicle speed usingEquation 3.

corrected vehicle speed=vehicle speed×(1−error rate)  [Equation 3]

For example, when the vehicle speed is 20 m/s and the error rate is−0.5, the corrected vehicle speed is 30 m/s.

As described above, since the vehicle speed is corrected using therelative vehicle speed, the vehicle speed may be accurately determinedeven when an abnormality occurs at the wheel speed sensor or the wheel.

Hereinafter, a vehicle control method for correcting a vehicle speedaccording to one embodiment of the present disclosure will be describedin detail with reference to the accompanying drawings.

As illustrated in FIG. 4, a vehicle control method according to oneembodiment of the present disclosure includes measuring a vehicle speed(S110), calculating an error rate (S120), and correcting a vehicle speed(S130).

In the measuring of the vehicle speed (S110), a first vehicle speed anda second vehicle speed of a vehicle are measured.

The first vehicle speed may be a vehicle speed measured by a wheel speedsensor, and the second vehicle speed may be provided as a relative speedof an image captured by a camera with respect to the vehicle.

The second vehicle speed may be provided as the relative speed withrespect to the vehicle based on an increasing number of occupied pixelsof a portion of the image captured by the camera.

The second vehicle speed may be provided as the relative speed withrespect to the vehicle based on a degree of movement of occupied pixelsof a portion of the image captured by the camera.

In the calculating of the error rate (S120), an error rate of a vehiclespeed is calculated using the first vehicle speed and the second vehiclespeed measured in the measuring of the vehicle speed (S110).

The error rate may be proportional to the sum of the first vehicle speedand the second vehicle speed and may be inversely proportional to thefirst vehicle speed.

In the correcting of the vehicle speed (S130), a third vehicle speed ofthe vehicle is calculated based on the error rate calculated in thecalculating of the error rate (S120), and the vehicle speed iscorrected.

The third vehicle speed may be provided to be proportional to the firstvehicle speed and a difference between a reference value and the errorrate.

The reference value may be set to 1.

Hereinafter, a vehicle control apparatus for detecting a wheelabnormality according to one embodiment of the present disclosure willbe described in detail with reference to the accompanying drawings.

In addition, the vehicle control apparatus for detecting a wheelabnormality according to one embodiment of the present disclosure may beapplied to a vehicle including at least one wheel, and hereinafter, thevehicle control apparatus applied to a general vehicle including fourwheels will be described.

As illustrated in FIG. 5, the vehicle control apparatus according to oneembodiment of the present disclosure includes a sensor 210, an imageacquisition unit 220, and a controller 230.

Because a structure and a function of the image acquisition unit 220 arethe same as those of the above-described image acquisition unit 120, adetailed description thereof will be omitted.

The sensor 210 detects a vehicle speed.

The sensor 210 may detect a wheel speed and transfer the detectionresult to the controller 230.

The sensor 210 may include a plurality of wheel speed sensors installedeach of wheels to detect wheel speeds.

Each of the plurality of wheel speed sensors may include a tone wheelinstalled at a wheel of the vehicle and configured to rotate with thewheel and a sensing unit that measures a period of a pulse signalgenerated when the tone wheel rotates.

The controller 230 includes a relative speed calculator 231, an errorrate calculator 232, a wheel speed corrector 233, and a wheelabnormality determination unit 234.

Because a structure and a function of the relative speed calculator 231are the same as those of the above-described relative speed calculator131, a detailed description thereof will be omitted.

The error rate calculator 232 calculates an error rate of each of wheelspeeds using a relative speed and each of the wheel speeds.

A plurality of error rates may be provided based on the wheel speeds.

The error rate calculator 232 may calculate the error rate of each ofthe wheel speeds using Equation 4.

first error rate=(relative speed+first wheel speed)/first wheel speed

second error rate=(relative speed+second wheel speed)/second wheel speed

third error rate=(relative speed+third wheel speed)/third wheel speed

fourth error rate=(relative speed+fourth wheel speed)/fourth wheelspeed  [Equation 4]

For example, when the relative vehicle speed is −30 m/s, and the firstwheel speed is 20 m/s, the first error rate is −0.5.

In addition, when the second wheel speed to the fourth wheel speed are30 m/s, the second error rate to the fourth error rate is zero.

The wheel speed corrector 233 corrects a wheel speed based on the errorrate.

A plurality of corrected wheel speeds may be provided based on the wheelspeeds.

The wheel speed corrector 233 may correct the wheel speed using Equation5.

first corrected wheel speed=first wheel speed×(1−first error rate)

second corrected wheel speed=second wheel speed×(1−second error rate)

third corrected wheel speed=third wheel speed×(1−third error rate)

fourth corrected wheel speed=fourth wheel speed×(1−fourth errorrate)  [Equation 5]

For example, when the first wheel speed is 20 m/s and the first errorrate is −0.5, the first corrected vehicle speed is 30 m/s.

In addition, when the second wheel speed to the fourth wheel speed are30 m/s and the second error rate to the fourth error rate are zero, thesecond to fourth corrected vehicle speed is 30 m/s.

The wheel abnormality determination unit 234 compares each of the wheelspeeds and each of the corrected wheel speeds and determines a wheelabnormality.

The wheel abnormality determination unit 234 may respectively comparethe first wheel speed through the fourth wheel speed with the firstcorrected wheel speed through the fourth corrected wheel speed, and thewheel abnormality determination unit 234 may inform of an abnormality ofthe corresponding wheel when each difference between them is a referencevalue or more.

As described above, since each of the wheel speeds is corrected usingeach of the wheel speeds and the relative vehicle speed and each of thecorrected wheel speeds is compared with each of the uncorrected wheelspeeds, a wheel in which an abnormality occurs may be quickly andaccurately determined.

Hereinafter, a vehicle control method for detecting a wheel abnormalityaccording to one embodiment of the present disclosure will be describedin detail with reference to the accompanying drawings.

As illustrated in FIG. 6, a vehicle control method according to oneembodiment of the present disclosure may include measuring a vehiclespeed (S210), calculating an error rate (S220), correcting a wheel speed(S230), determining a wheel abnormality (S240), and informing a driverof an abnormal wheel (S250).

In the measuring of the vehicle speed (S210), a first vehicle speed anda second vehicle speed of a vehicle are measured.

The first vehicle speed may be a vehicle speed measured by a wheel speedsensor, and the second vehicle speed may be provided as a relative speedof a vehicle image captured by a camera with respect to the vehicle.

The second vehicle speed may be provided as the relative speed of theimage captured by the camera with respect to the vehicle.

The second vehicle speed may be provided as the relative speed withrespect to the vehicle based on an increasing number of occupied pixelsof a portion of the image captured by the camera.

The second vehicle speed may be provided as the relative speed withrespect to the vehicle based on a degree of movement of occupied pixelsof a portion of the image captured by the camera.

In the calculating of the error rate (S220), an error rate of a vehiclespeed is calculated using the first vehicle speed and the second vehiclespeed measured in the measuring of the vehicle speed (S210).

In the calculating of the error rate (S220), the error rate of thevehicle speed may be calculated a plurality of times using each of thewheel speeds included in the first vehicle speed and the second vehiclespeed.

The error rate may be proportional to the sum of the first vehicle speedand the second vehicle speed and may be inversely proportional to thefirst vehicle speed.

In the correcting of the vehicle speed (S230), a third vehicle speed ofthe vehicle is calculated based on the error rate calculated in thecalculating of the error rate (S220) and the vehicle speed is corrected.

In the correcting of the vehicle speed (S230), the third vehicle speedmay be calculated a plurality of times based on the plurality of errorrates calculated in the calculating of the error rate (S220).

The third vehicle speed may be proportional to the first vehicle speedand a difference between a reference value and the error rate.

The reference value may be set to 1.

In the determining of the wheel abnormality (S240), the third vehiclespeed calculated in the correcting of the vehicle speed (S230) and thefirst vehicle speed are compared and a wheel abnormality of the vehicleis determined.

In the determining of the wheel abnormality (S240), the plurality ofthird vehicle speeds calculated in the correcting of the vehicle speed(S230) and a plurality of first vehicle speeds are respectively comparedand an abnormality of each wheel of the vehicle may be determined.

Accordingly, the correcting of the vehicle speed (S230) may furtherinclude correcting the first vehicle speed using the calculated thirdvehicle speed. In the determining of the wheel abnormality (S240), awheel in which a difference between each of the plurality of thirdvehicle speeds calculated in the correcting of the vehicle speed (S230)and each of the plurality of first vehicle speeds is a reference valueor more may be determined as an abnormal wheel.

In the informing the driver of the abnormal wheel (S250), the wheel inwhich an abnormality is discovered in the determining of the wheelabnormality (S240) is informed to a driver.

As is apparent from the above description, a vehicle control method inaccordance with one embodiment of the present disclosure has an effectin that a vehicle speed can be accurately determined even when anabnormality occurs at a wheel because a first vehicle speed and a secondvehicle speed of a vehicle are measured to correct the vehicle speed.

Although one embodiment of the present disclosure has been illustratedand described, the present disclosure may not be limited to theabove-described specific embodiment and various changes may be made inthe embodiment by those skilled in the art without departing from thescope and spirit of the present disclosure defined by the appendedclaims, and such modifications may not be individually understood fromthe present disclosure.

REFERENCE NUMERALS

-   -   110: SENSING UNIT    -   120: IMAGE ACQUISITION UNIT    -   130: CONTROLLER    -   131: RELATIVE SPEED CALCULATOR    -   132: ERROR RATE CALCULATOR    -   133: VEHICLE SPEED CORRECTOR

1. A vehicle control method comprising: measuring a vehicle speed tomeasure a first vehicle speed and a second vehicle speed of a vehicle;calculating an error rate to calculate an error rate of a vehicle speedusing the first vehicle speed and the second vehicle speed measured inthe measuring of the vehicle speed; and correcting a vehicle speed tocorrect a speed of the vehicle by calculating a third vehicle speed ofthe vehicle based on the error rate calculated in the calculating of theerror rate.
 2. The vehicle control method of claim 1, further comprisingdetermining a wheel abnormality to determine a wheel abnormality of thevehicle by comparing the third vehicle speed calculated in thecorrecting of the vehicle speed with the first vehicle speed.
 3. Thevehicle control method of claim 1, wherein the first vehicle speed is aspeed of the vehicle measured by a wheel speed sensor, and the secondvehicle speed is a relative speed of an image captured by a camera withrespect to the vehicle.
 4. The vehicle control method of claim 1,wherein the error rate is proportional to the sum of the first vehiclespeed and the second vehicle speed and is inversely proportional to thefirst vehicle speed.
 5. The vehicle control method of claim 1, whereinthe third vehicle speed is proportional to the first vehicle speed and adifference between a reference value and the error rate.
 6. The vehiclecontrol method of claim 1, wherein the second vehicle speed is arelative speed with respect to the vehicle based on an increased numberof occupied pixels of a portion of an image captured by a camera.
 7. Thevehicle control method of claim 1, wherein the second vehicle speed is arelative speed with respect to the vehicle based on a degree of movementof occupied pixels of a portion of an image captured by a camera.
 8. Thevehicle control method of claim 5, further comprising correcting thefirst vehicle speed using the calculated third vehicle speed.
 9. Thevehicle control method of claim 2, wherein: the first vehicle speedincludes each wheel speed; the calculating of the error rate includescalculating the error rate of the vehicle speed a plurality of timesusing each wheel speed included in the first vehicle speed and thesecond vehicle speed; and the calculating of the error rate includescalculating the third vehicle speed of the vehicle a plurality of timesbased on the plurality of error rates calculated in the calculating ofthe error rate.
 10. The vehicle control method of claim 9, wherein thedetermining of the wheel abnormality includes determining an abnormalityof each of the wheels of the vehicle by respectively comparing theplurality of third vehicle speeds calculated in the vehicle speedcorrection operation with the wheel speeds included in the first vehiclespeed.
 11. A vehicle control apparatus comprising: a camera configuredto capture a running image of a vehicle; a plurality of wheel speedsensors installed at each wheel of the vehicle; and a controllerconfigured to correct a plurality of wheel speeds using the runningimage obtained by the camera and a detection result of the wheel speedsensors, wherein the controller includes: a relative speed calculatorconfigured to calculate a relative speed of the vehicle using therunning image captured by the camera; an error rate calculatorconfigured to calculate an error rate of the wheel speed using therelative speed and each of the wheel speeds; and a vehicle speedcorrector configured to correct each of the wheel speeds based on theerror rate.
 12. The vehicle control apparatus of claim 11, wherein thecontroller further includes a wheel abnormality determination unitconfigured to respectively compare the wheel speeds detected by theplurality of wheel speed sensors and the corrected wheel speeds todetermine a wheel abnormality.
 13. The vehicle control apparatus ofclaim 11, wherein: the relative speed calculator calculates the relativespeed of the vehicle based on an increased number of occupied pixels ofa portion of the image captured by the camera; the error rate calculatorcalculates the error rate of the vehicle such that the error rate isproportional to a vehicle speed and the relative speed and inverselyproportional to the vehicle speed; and the vehicle speed correctorcorrects each of the wheel speeds based on a corrected vehicle speedproportional to the vehicle speed and a difference between a referencevalue and the error rate.
 14. The vehicle control method of claim 2,wherein the first vehicle speed is a speed of the vehicle measured by awheel speed sensor, and the second vehicle speed is a relative speed ofan image captured by a camera with respect to the vehicle.
 15. Thevehicle control method of claim 2, wherein the error rate isproportional to the sum of the first vehicle speed and the secondvehicle speed and is inversely proportional to the first vehicle speed.16. The vehicle control method of claim 2, wherein the third vehiclespeed is proportional to the first vehicle speed and a differencebetween a reference value and the error rate.
 17. The vehicle controlmethod of claim 2, wherein the second vehicle speed is a relative speedwith respect to the vehicle based on an increased number of occupiedpixels of a portion of an image captured by a camera.
 18. The vehiclecontrol method of claim 2, wherein the second vehicle speed is arelative speed with respect to the vehicle based on a degree of movementof occupied pixels of a portion of an image captured by a camera. 19.The vehicle control apparatus of claim 12, wherein: the relative speedcalculator calculates the relative speed of the vehicle based on anincreased number of occupied pixels of a portion of the image capturedby the camera; the error rate calculator calculates the error rate ofthe vehicle such that the error rate is proportional to a vehicle speedand the relative speed and inversely proportional to the vehicle speed;and the vehicle speed corrector corrects each of the wheel speeds basedon a corrected vehicle speed proportional to the vehicle speed and adifference between a reference value and the error rate.